1. Field of the Invention
The present invention relates to automatic identification systems and methods such as are used in identifying products or parts, based on coded symbols (e.g., bar codes) carried by the products or parts.
2. Background of the Invention
Technological advancements in the areas of automatic identification have reached a point in their development where a near paperless manufacturing, configuration and distribution system is achievable. The central element supporting this near paperless system is the software by which products or inventory are accounted and tracked. This software exists in various forms (such as the very mature MRP II) and in general, these variations are application dependent. A manufacturing operation relies on such a system for inventory control, product routing, and decision support for timely purchasing to fill a bill of materials for production planning. Similar software exists for tracking inventory through a logistics or property system, and the popularity of configuration management, a requirement once relegated to the aerospace industry, is growing in the commercial sector.
The current method used for interfacing with inventory and configuration management systems usually involves a mixture of manual and automated data entry. Such automated data entry commonly uses bar codes. These bar codes typically are printed on adhesive backed paper labels which are attached to the product, on the product labels, or on the product container. In grocery stores and similar consumer outlets, the bar code is a part of the label and identifies the product to the computer through the use of a scanner which scans the bar code. Inventory records are adjusted when an item is sold. The product can be tracked through its life cycle to point of sale if necessary, by use of the bar code printed on the label. However, many other consumer outlets, such as those selling automotive parts, lose the product identification when the product and its container are separated. There is no matching machine-readable identifier marked permanently on the surface of the product or embedded in the product for tracking the product through its life cycle or for use in latent validation of configuration.
The methods currently being used to image a two dimensional symbol on a product generally involve the use of laser or optical devices. Typical two dimensional symbols are discussed below and include two basic types, tiered or stacked bar codes and matrix symbols. Most of the methods used for scanning the stacked bar code versions of the two dimensional symbology family are laser based. The laser is best suited to scanning on matte finish labels or paper surfaces. The scanners for the matrix versions of the symbology family are camera based, usually a charged coupled device (CCD) or CMOS. Use of the CCD is the preferred method for scanning symbols that have been applied directly to the substrate of a product.
These scanning methods achieve their scanning function by optically imaging those marks which are visible on the substrate. The sensing mechanism is based on illumination, whether natural or induced, of one symbol to make the image of the symbol optically apparent to the scanner. Thus, these scanning methods are not suitable for invisible surface marks or subsurface marks which cannot be made visible without stimulation, e.g., UV ink.
The standard method for marking products with identification marks or symbols involves the use of methods such as label application, ink jet printing, machine engraving, laser etching, micro-abrasive blast, micro-machining and dot peening. These methods produce marks that are visible and must be read by optical devices, primarily lasers, CCDs and CMOS. This approach limits the location of a product identifier to the surface of the product.
In distribution and logistics applications there are usually many products packed in a container for efficient transportation. These containers can be made of cardboard, wood or other materials. With standard marking and scanning methods, labels on the outside of the container provide the only identification markings for determining the contents of the container without opening the container for examination. Further, labels fall off and get damaged.
In many applications where products have foam coverings, laminants and multi-layer features, optical methods are limited to surface identification and are not capable of interrogating surface identification marks that have been covered. Accordingly, there is no opportunity in these applications for latent validation of the configuration using optical device.
Generally speaking, the invention involves the use of radar to detect and image two dimensional identification marks or symbols for both surface and subsurface conditions.
According to a first aspect of the invention, a method is provided for sensing two-dimensional identification marks provided on or within a substrate in such a manner that the marks can be differentiated by radar from the substrate, the method comprising: transmitting a radar pulse to a target area of the substrate provided with the two dimensional identification marks, detecting radar echoes from the target area produced by radar reflection from the identification marks in response to the radar pulse; and processing data based on the echoes to produce an image of the identification marks.
In an embodiment where the identification marks are embedded in the substrate and in other applications, the radar pulse is preferably transmitted into the substrate using microwave impulse radar, and any echoes that are returned after a predetermined time after transmission of said radar pulse are detected. In this embodiment, a series of radar pulses are transmitted into the substrate at different signal depths based on the timing of any echo returns, until an echo return at signal depth corresponding to the distance to identification marks is received.
In another embodiment, the identification marks and the substrate are of different densities and the radar echoes are detected based on the density of the identification marks.
In yet another embodiment, the identification marks and the substrate are made of materials having different radar reflection characteristics, and the radar echoes are detected based on radar reflection characteristics of the identification marks.
Advantageously, the identification marks comprise a two dimensional matrix symbol, although other two dimensional marks or symbols such as tiered or stacked bar codes can also be used.
In accordance with a further aspect of the invention, an apparatus or system is provided for identifying radar reflective or radar absorptive machine-readable identification marks on a substrate, the apparatus comprising: a micropower impulse radar imager means for transmitting radar pulses to a target area including the identification marks and for receiving returned radar energy; converter means for converting the returned radar energy into information signals; computer means for analyzing the information signals to determine the information contained in the identification marks; and display means for displaying the information so obtained in a human-readable format.
Further features and advantages of the present invention will be set forth in, or apparent from, the detailed description of preferred embodiments thereof which follows.